Nakum and Yaxha during the Terminal Classic Period: External Relations and Strategies of Survival at the Time of the Collapse. Bernard Hermes and Jarosław Źrałka. Contributions in New World Archaeology 4: 175-204. Kraków 2012 Jarosław Źrałka

https://www.academia.edu/7762399/Nakum_and_Yaxha_during_the_Terminal_Classic_Period_External_Relations_and_Strategies_of_Survival_at_the_Time_of_the_Collapse_Bernard_Hermes_and_Jaros%C5%82aw_%C5%B9ra%C5%82ka_Contributions_in_New_World_Archaeology_4_175_204_Krak%C3%B3w_2012